logd: drop mSequence from LogBufferElement

Use getRealTime() instead and leverage private liblog log_time
comparison and math functions.  This saves 8 bytes off each
element in the logging database.

Test: gTest liblog-unit-tests logd-unit-tests logcat-unit-tests
Bug: 35373582
Change-Id: Ia55ef8b95cbb2a841ccb1dae9a24f314735b076a
diff --git a/logd/LogTimes.h b/logd/LogTimes.h
index 23fdf4e..9a3ddab 100644
--- a/logd/LogTimes.h
+++ b/logd/LogTimes.h
@@ -51,13 +51,13 @@
    public:
     LogTimeEntry(LogReader& reader, SocketClient* client, bool nonBlock,
                  unsigned long tail, unsigned int logMask, pid_t pid,
-                 uint64_t start, uint64_t timeout);
+                 log_time start, uint64_t timeout);
 
     SocketClient* mClient;
-    uint64_t mStart;
+    log_time mStart;
     struct timespec mTimeout;
     const bool mNonBlock;
-    const uint64_t mEnd;  // only relevant if mNonBlock
+    const log_time mEnd;  // only relevant if mNonBlock
 
     // Protect List manipulations
     static void lock(void) {